Another piece of the puzzle of apoptotic cytochrome c release.

Involvement of the mitochondrial permeability transition pore (PTP) in apoptosis and PTP structure are highly controversial. In this issue of Molecular Microbiology, experiments based on yeast genetics analyse the roles of the three proteins commonly considered to form the PTP, i.e. porin, ADP/ATP carrier (ACC) and mitochondrial cyclophilin, on apoptosis-like cell death. Whereas knocking out cyclophilin had no effect, the porin-1 knockout yeast showed enhanced apoptosis, suggesting that porin-1 has an antiapoptotic role. Loss of the ACC proteins afforded protection against some causes of death, but enhanced death induced by H(2)O(2), suggesting a more complex role for the ACC proteins in regulating apoptosis-like death in yeast.